Pigtail connection



Aug. 21, 1923. 1,465,255

F.. F. DORSEY PIGTAIL CONNECTION Filed Oct. 19 1921 Hnwntcwrr PatentedAug. 21, 1923.

UNITED STATES PATENT OFFICE.

FARNUM I. DORSEY, OF ROCHESTER, NEW YORK, ASSIG'NOR TO NORTH EASTELECTRIC COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

' PIGTAIL CONNECTION.

Application filed October 19, 1921.

To all whom it may concern:

Be it knownthat I, FARNUM F. DORSEY, a citizen of the United States,residing at Rochester, in the county of Monroe and State of New York,have invented certain new and useful Improvements in PigtailConnections; and I do hereby declare the following to be a full, clear,and exact description of the invention, such as will enable othersskilled in the art to which it appertains to make and use the same.

This invention relates to the flexible connectors or pig-tails used .inconnection with brushes, for dynamo-electric machines, which are made ofcarbon or of compounds of carbon and metal. It is common to secure thepig-tails in holes drilled in such brushes, by tamping metallicmaterial'into the holes around the ends of the pig-tails.

The object of the present invention is to producea pig-tail connection,in the manner referred to, which shall be inexpensive and secure, and inwhich a good conductive engagement between the pig-tail and thebrush-material shall be assured. I have discovered that this can beaccomplished by using, as the material for securing the pigtail,stranded wireor cable either identical with or similar to that of whichthe pigtail itself is composed, this material being coiled around theend of the pig-tail and being tamped into a firm mass in -the hole whichreceives the pig-tail.

In the accompanying drawings, Fig. 1 is 5 a part-1y sectional elevationshowing a brush provided with two holes, in one of which is a pig-tailwhich has been secured in the manner described herein, while a pig-tailin process of attachment is shown in the other hole. Fig. 2 shows apig-tail to which the bonding material has been applied in a A differentmanner.

Pigtails are usually made in the form of cables or stranded conductors,consisting of numerous fine wires of soft copper. I have found that thissame material or a similar material of any soft metal, constitutes anexcellent bonding-material for the pig-tail. As shown in Fig. 1 of thedrawings, the matethe coils 1 Serial No.- 508,853.

rial of the pi g-tail 3 has been merely bentback and wound around thebody of thepig-tail, so as to produce a series of coils 4. The pig-tailis then introduced into the hole in the brush 5, and by means of asuitabletoolG pressure is applied to the coils 4, suflicient to compressthem into a compact mass which closely fills the lower part of the holeand presses tightly iigainst its walls, as shown at the right of Thestrands of the wire used as bonding- Inaterial lie in the direction inwhichv they present the maximum frictional resistance to withdrawal ofthe pig-tail. The arrangement has also increased effectiveness owing tothe fact that the pig-tail, being continuous with the lowermost coil 4,cannot be withdrawn without withdrawing all of the compacted coils in amass, so that the cnrity of the pig-tail depends, not on frictionbetween the pig-tail and the bondingmaterial, but upon the friction atthe greater area of contact between the bonding-material and the brush.

In place of making the coils of bondingmaterial continuous with thepig-tail, they may be made separate as in Fig. 2, where are made of aseparate piece of stranded conductor wrapped around the pigtail 8, andthe lower end 10 of the latter is bent back and spreadout against theouter surfaces of the coils, so as to anchor it securely.

The invention claimed is:

1. The combination, with a carbon brush or the like provided With ahole, of a stranded conductor extending into thehole, and bent back andcoiled around itself, with the coils compacted together and compressedinto frictional engagement with the walls of the hole to secure theconductor to the brush.

2. The method of attaching a pig-tail connector to a brush, whichconsists in winding coils of stranded wire conductor around the end ofthe pig-tail, introducing said end and the coiled material into a holein the brush, and tamping the coiled material into a compact mass.

. FARNUM F. DORSEY.

